KR101903816B1 - Pu rigid foam with low thermal conductivity and good thermal stability - Google Patents

Abstract

The present invention relates to a composition comprising at least one polyether polyol as component (A), at least one polyether polyol based on at least one amine as component (B), at least one polyester polyol as component (C) and at least one polyisocyanate In the presence of at least one catalyst selected from the group consisting of salts of carboxylic acids having from 1 to 20 carbon atoms as the component (E), amine-containing compounds and mixtures thereof, and at least one blowing agent as component (F) (ISO Index) of from 140 to 180, which is the ratio of OCN to OH groups. The invention further relates to a process for the production of said polyurethane foam, its use for insulation, in particular for insulation of pipes, and also to a pipe insulation comprising a polyurethane foam according to the invention.

Description

[0001] PU RIGID FOAM WITH LOW THERMAL CONDUCTIVITY AND GOOD THERMAL STABILITY [0002]

The present invention relates to a composition comprising at least one polyether polyol as component (A), at least one polyether polyol based on at least one amine as component (B), at least one polyester polyol as component (C) and at least one polyisocyanate In the presence of at least one catalyst selected from the group consisting of salts of carboxylic acids having from 1 to 20 carbon atoms as the component (E), amine-containing compounds and mixtures thereof, and at least one blowing agent as component (F) (ISO Index) of from 140 to 180, which is the ratio of OCN to OH groups. The invention further relates to a process for the production of said polyurethane foam, its use for insulation, in particular for insulation of pipes, and also to a pipe insulation comprising a polyurethane foam according to the invention.

Polyurethane foams which can be used for insulation of pipes are already known in the prior art.

US 2006/0052467 discloses polyol compositions suitable for processing with suitable polyisocyanates to provide foams.

DE 10 2004 001 317 A1 discloses a polyurethane foam for pipe insulation. This polyurethane foam can be obtained by reacting an isocyanate component (a) with a polyol mixture (b), wherein the polyol mixture comprises a polyol having a hydroxyl value of greater than 70 mg KOH / g and is prepared according to DIN 53019 And has a viscosity of less than 3000 mPa 측정 measured. This document discloses that compounds generally having two or more groups reactive with isocyanates, such as polyols, are possible. As examples, there are compounds having an OH group, an SH group, and / or an NH ₂ group.

EP 1 288 239 A1 discloses a process for preparing solid urethane-polyisocyanurate foams. This includes various polyol polyethers.

WO 98/37116 also discloses a process for preparing solid polyurethane foams by reacting a polyisocyanate component with a mixture of polyol components. According to this document, the polyisocyanate component is a polymethylene polyphenyl polyisocyanate compound or a derivative thereof. The mixture of polyol components includes a polyol obtained by bonding an alkylene oxide to an aliphatic amine and an aromatic polyether polyol obtained by bonding an alkylene oxide to an aromatic amine.

US 2003/0134923 Al likewise discloses a polyurethane foam comprising the reaction product of an organic polyisocyanate and a polyester polyol.

WO 2005/090432 A1 discloses a process for preparing a solid polyurethane foam having an isocyanate index of 110 to 120 by reacting an organic polyisocyanate composition with a mixture reactive with isocyanate groups. In addition to polyester polyols, polyetherols based on aromatic amines are also present in the reaction mixture described.

EP 1 735 365 B1 discloses polyurethanes and processes for their preparation. For this purpose, the organic polyisocyanate composition is reacted with a composition that is reactive with isocyanate groups and comprises, for example, a polyether polyol or a polyester polyol polyol.

WO 00/63276 A1 discloses polyol mixtures for making rigid polyurethane foams. This mixture comprises an addition product of an alkylene oxide on an aromatic diamine or polyamine. The polyester polyol polyol may also be present as a compound that is reactive toward isocyanate groups.

The known polyurethane foams from the prior art still need to be improved with respect to their thermal conductivity and thermal behavior. In particular, the thermal conductivity of the polyurethane foam according to the prior art can be reduced without impairing thermal stability.

Therefore, in view of the prior art, it is an object of the present invention to provide a polyurethane foam having a characteristic profile which is particularly stable and advantageous with respect to thermal conductivity and thermal stability. Since the polyurethane foam according to the invention will be used, for example, as an insulator, especially as a pipe insulator, a polyurethane foam with a particularly low thermal conductivity should be provided. In addition to low thermal conductivity, the polyurethane foam of the present invention should have good thermal stability.

According to the present invention,

(A) at least one polyether polyol as component (A)

(B) at least one polyether polyol based on at least one amine as component (B)

(C) at least one polyester polyol as component (C) and

(D) at least one polyisocyanate as component (D)

In the presence of at least one catalyst selected from the group consisting of salts of carboxylic acids having 1 to 20 carbon atoms as component (E), amine-containing compounds and mixtures thereof, and at least one blowing agent as component (F) , And a ratio of OCN group to OH groups (ISO index) of from 140 to 180.

Furthermore, the above objects are achieved by a process for producing a polyurethane foam according to the invention comprising at least the following steps:

(I) contacting the components (A), (B), (C), (D), (E) and (F)

(II) foaming the reaction product obtained in step (I).

The above objects are also achieved by the use for insulation of the polyurethane foam of the present invention and by the insulated pipe comprising the polyurethane foam according to the invention.

The individual components of the polyurethane foam of the present invention are described in detail below:

Component (A):

One or more polyether polyols are present as component (A) in the polyurethane foam according to the invention. For the purposes of the present invention, all polyether polyols known to those skilled in the art are generally suitable as component (A).

It is preferable to use a polyether polyol based on at least one polyhydric alcohol as the component (A).

According to the present invention, a polyether polyol having two or more hydrogen atoms reactive with isocyanate, preferably a polyether polyol having OH value in the range of 100 to 1200 mg KOH / g is preferably used as component (A).

The polyether polyols which are preferably used have a functionality ranging, for example, from 2 to 8, in particular from 3 to 8.

The polyether polyols preferably used as component (A) are prepared by methods known to those skilled in the art, for example, by anionic polymerization of alkylene oxides in the presence of a catalyst, preferably an alkali metal hydroxide.

As alkylene oxides, ethylene oxide and / or propylene oxide, preferably pure 1,2-propylene oxide, are conventionally used.

The starting molecule used is, in particular, a compound having 2 or more, preferably 3 to 8, hydroxyl groups in the molecule.

Glycerol, pentaerythritol, a sugar compound such as glucose, sorbitol, mannitol and sucrose, a polyhydric phenol, a resole such as a phenol and a phenol, as a starting molecule having 2 or more, preferably 3 to 8, Oligomer condensation products of aldehydes and Mannich condensates of phenol, formaldehyde and dialkanolamine, and also melamine are preferably used.

Accordingly, the present invention is preferably directed to a process for the preparation of polyether polyols, wherein at least one polyether polyol (component A) is selected from the group consisting of trimethylolpropane, glycerol, pentaerythritol, sugar compounds such as glucose, sorbitol, mannitol and sucrose, polyhydric phenols, An oligomer condensation product of aldehyde, and a Mannich condensation product of phenol, formaldehyde and dialkanol amine, melamine, and mixtures thereof. The present invention provides a polyurethane foam of the present invention.

The polyether polyols used as component (A) preferably have a functionality of from 3 to 8. Furthermore, the polyether polyol used as component (A) preferably has a hydroxyl value of from 100 mg KOH / g to 1200 mg KOH / g, in particular from 240 mg KOH / g to 570 mg KOH / g.

In a preferred embodiment, for example, a mixture of 2, 3, 4 or 5 polyether polyols different for the starting molecule and / or alkylene oxide used is used as component (A).

For example, a mixture comprising at least one polyether polyol based on the polysaccharide sugar as component (a1) is used as component (A). The polysaccharide sugar is preferably sucrose.

In a preferred embodiment, the polyether polyol used as component (a1) is not exclusively based on one or more polysaccharide sugars, but instead a plurality of polyhydric alcohols, for example selected from pentaerythritol and / or diethylene glycol, .

The polyether polyol used as component (a1) is, for example, 100 to 700 mg KOH / g, preferably 200 to 600 mg KOH / g, particularly preferably 300 to 500 mg KOH / g, Lt; RTI ID = 0.0 > KOH / g. ≪ / RTI >

In a further preferred embodiment, the polyether polyol used as component (a1) has an average functionality of, for example, from 2 to 6, preferably from 3 to 5, particularly preferably from 3.5 to 4.5.

In the mixture of polyether polyols preferably used as component (A), an additional polyether polyol (a2) based on at least one monosaccharide sugar is preferably present.

The monosaccharide sugar based on component (a2) is, for example, sorbitol.

The polyether polyol used as component (a2) is, for example, in the range of 200 to 800 mg KOH / g, preferably 300 to 700 mg KOH / g, particularly preferably 400 to 600 mg KOH / g, Lt; RTI ID = 0.0 > KOH / g. ≪ / RTI >

In a further preferred embodiment, the polyether polyol used as component (a2) has an average functionality of, for example, from 3 to 7, preferably from 4 to 6, particularly preferably from 4.5 to 5.5.

As a further polyether polyol present in a mixture of polyether polyols preferably used as component (A), at least one polyether polyol based on one or more dihydric alcohols is preferably present as component (a3) in the mixture.

The dihydric or higher alcohol present in component (a3) can be divalent, trivalent, tetralic or pentavalent, i.e. it contains 2, 3, 4 or 5 hydroxy groups per molecule.

Particularly preferred dihydric or higher alcohols present in component (a3) are, for example, glycerol.

In a further preferred embodiment, the polyether polyol used as component (a3) is, for example, from 500 to 1100 mg KOH / g, preferably from 600 to 1000 mg KOH / g, particularly preferably from 700 to 900 mg OH < / RTI > of KOH / g.

In a further preferred embodiment, the polyether polyols used as component (a3) have an average functionality of, for example, from 1 to 5, preferably from 2 to 4, particularly preferably from 2.5 to 3.5.

In a particularly preferred embodiment, at least one polyether polyol (a1) based on a polysaccharide sugar, at least one polyether polyol (a2) based on a monosaccharide sugar and at least one polyether polyol based on one or more alcohol a3) is used as component (A) in the polyurethane foam of the present invention.

The present invention therefore preferably relates to a composition comprising at least one polyether polyol (a1) based on a polysaccharide sugar, at least one polyether polyol (a2) based on a monosaccharide sugar, and at least one polyether polyol (a3) is used as component (A).

Component (A) is generally present in the polyurethane foam of the invention in each case in an amount of from 10 to 60% by weight, preferably from 20 to 60% by weight, based on the sum of components (A), (B), (C) By weight to 50% by weight, particularly preferably 25 to 45% by weight. When a mixture of various polyether polyols is used as component (A), the specified amount is based on this mixture.

The sum of components (A), (B), (C) and (E) is always 100% by weight according to the invention.

Component (B):

One or more polyether polyols based on one or more amines are present as component (B) in the polyurethane foam of the present invention. For the purposes of the present invention, all polyether polyols meeting the specified conditions are generally suitable as component (B).

The amine present in component (B) is, for example, selected from the group consisting of amines having at least two primary amino groups in the molecule, and aromatic diamines and / or polyamines such as phenylenediamine, 2,3-, 2,4-, 3,4- and 2,6-toluenediamine or 4,4'-, 2,4'- and 2,2'-diaminodiphenylmethane and also aliphatic diamines and polyamines such as ethylenediamine, Is preferably used.

Toluene diamine (TDA) is preferably used as the starting molecule for component (B), and one of the mentioned isomers, or a mixture of the aforementioned isomers, may be used.

Accordingly, the present invention preferably provides a polyurethane foam according to the invention wherein at least one amine in component (B) is toluene diamine (TDA).

The component (B) of the polyurethane foam of the present invention is, for example, an alkylene oxide such as tetrahydrofuran, ethylene oxide, propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and And mixtures thereof, preferably a mixture of ethylene oxide and propylene oxide, is obtained by reacting the above-mentioned amine with an alkylene oxide, preferably an ethylene oxide and a propylene oxide. The reaction conditions for this reaction are known per se to the person skilled in the art.

In a further preferred embodiment, the polyether polyol used as component (B) is, for example, 100 to 700 mg KOH / g, preferably 200 to 600 mg KOH / g, particularly preferably 300 to 500 mg KOH / g, very particularly preferably from 350 to 450 mg KOH / g.

The polyether polyols used as component (B) in a further preferred embodiment have, for example, an average functionality of from 1 to 6, preferably from 2 to 5, particularly preferably from 3 to 4.5.

Component (B) is generally present in the polyurethane foam of the invention in each case in an amount of from 10 to 50% by weight, preferably from 10 to 50% by weight, based on the sum of components (A), (B), (C) 20 to 40% by weight, particularly preferably 25 to 35% by weight.

Component (C):

One or more polyester polyols are present as component (C) in the polyurethane foam of the present invention.

The polyester polyols used as component (C) are preferably polyfunctional alcohols having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, preferably diols such as ethylene glycol, diethylene Glycol, butanediol, trimethylol propane, glycerol or pentaerythritol with a polyfunctional carboxylic acid having 2 to 12 carbon atoms such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, Dicarboxylic acid, maleic acid, fumaric acid, preferably phthalic acid, isophthalic acid, terephthalic acid, regenerated polyethylene terephthalate and isomers of naphthalenedicarboxylic acid or anhydrides thereof.

Polyesterol prepared from phthalic anhydride and / or terephthalic acid and / or recycled polyethylene terephthalate is particularly preferred. It is also possible to use hydrophobic materials simultaneously as an additional starting material in the production of polyester. The hydrophobic material is a water insoluble material containing a nonpolar organic radical and also having at least one reactive group selected from hydroxyl, carboxylic acid, carboxylic acid ester and mixtures thereof. The equivalent weight of the hydrophobic material is in the range of 130 to 1000 g / mol. For example, the use of fatty acids such as stearic acid, oleic acid, palmitic acid, lauric acid or linoleic acid and also fats and oils such as castor oil, cone oil, sunflower oil, coconut oil, olive oil, It is possible. When the polyester comprises a hydrophobic substance, the proportion of the hydrophobic substance based on the total monomer content of the polyesterol is preferably 1 to 30 mol%, particularly preferably 4 to 15 mol%.

In a particularly preferred embodiment, a polyester polyol made from phthalic anhydride, diethylene glycol and oleic acid is present as component (C).

The polyester polyols used according to the invention as component (C) generally have a functionality of from 1.5 to 8, preferably from 1.5 to 5, particularly preferably from 1.5 to 3. [

The polyester polyol used according to the invention as component (C) generally has a solubility in the range of from 100 mg KOH / g to 850 mg KOH / g, preferably from 100 mg KOH / g to 400 mg KOH / g, in particular 150 mg KOH / g To 300 mg KOH / g.

Component (C) is generally present in the polyurethane foam of the invention in each case in an amount of from 10 to 50% by weight, preferably from 20 to 20% by weight, based on the sum of components (A), (B), (C) To 40% by weight, particularly preferably 25% to 35% by weight.

Component (D):

One or more polyisocyanates are present as component (D) in the polyurethane foam of the present invention. For purposes of the present invention, conventional aliphatic, cycloaliphatic and especially aromatic diisocyanates and / or polyisocyanates can be used as polyisocyanates.

Specific examples that may be mentioned include tolylene 2,4- and 2,6-diisocyanate (TDI) and the corresponding isomer mixtures, diphenylmethane 4,4'-, 2,4'- and 2,2'-di Isocyanate (MDI) and corresponding isomer mixtures, mixtures of diphenylmethane 4,4'- and 2,4'-diisocyanate, polyphenylpolymethylene polyisocyanates, diphenylmethane 4,4'-, 2,4'- And mixtures of 2,2'-diisocyanate and polyphenylene polymethylene polyisocyanate (crude MDI) and mixtures of crude MDI and tolylene diisocyanate. Organic diisocyanates and polyisocyanates can be used individually or in the form of mixtures.

Modified multifunctional isocyanates, i.e., products obtained by chemical reaction of organic diisocyanates and / or polyisocyanates, are also commonly used. Examples which may be mentioned are diisocyanates and / or polyisocyanates comprising isocyanurate and / or urethane groups. The modified polyisocyanates are optionally mixed or unmodified organic polyisocyanates, such as diphenylmethane 2,4'-, 4,4'-diisocyanate, crude MDI, tolylene 2,4- and / or 2,6 -Diisocyanate. ≪ / RTI >

In addition, it is also possible to use the reaction product of a polyfunctional isocyanate and a polyhydric polyol and also mixtures of these with other diisocyanates and polyisocyanates.

Crude MDI having an NCO content of 29 to 33% by weight has been found to be particularly useful, such as organic polyisocyanates.

In a preferred embodiment, the polyisocyanate is selected to have a viscosity of less than 1000 mPas, preferably 100 to 1000 mPas, particularly preferably 120 to 1000 mPas, measured according to DIN 53019 at 20 占 폚.

The polyisocyanate used as component (D) in a further preferred embodiment has an average functionality of, for example, from 1 to 6, preferably from 2 to 4, particularly preferably from 2.5 to 3.5.

In a particularly preferred embodiment, it has an NCO content of 20 to 40% by weight, preferably 25 to 35% by weight, for example 31.5% by weight, and has a content of 2 to 4, preferably 2.5 to 3.5, A mixture of diphenylmethane 1,4'-diisocyanate and a highly functional oligomer and isomer (Crude MDI), having an average functionality, is present as component (D).

Component (D) is generally present in the polyurethane foam of the invention in each case in an amount of from 100 to 250% by weight, preferably from 160 to 250% by weight, based on the sum of components (A), (B), (C) To 200% by weight, particularly preferably 170 to 190% by weight.

Component (E):

The polyurethane foam of the present invention can be produced by reacting the above-mentioned components (A), (B), (C) and (D) with a salt of a carboxylic acid having from 1 to 20 carbon atoms as component (E) Or a mixture thereof, in the presence of at least one catalyst.

Compounds referred to as catalysts are known per se and are commercially available to those skilled in the art.

In one embodiment of the polyurethane foams of the present invention, preferably from 1 to 20 carbon atoms, which catalyze a crosslinking reaction to form allophanates, biurets or trimerization to form isocyanurates, A salt of a carboxylic acid having two carbon atoms is used as a catalyst in the production of the foam.

Examples of suitable salts are metal salts of the corresponding carboxylic acids, in particular ammonium salts, alkali metal salts such as Li, Na, K, Rb or Cs salts or alkaline earth metal salts such as Be, Mg, Ca, Sr or Ba There is salt. Substituted or unsubstituted, saturated or unsaturated, aliphatic or aromatic carboxylic acids having 1 to 20 carbons, such as formic acid, acetic acid, octanoic acid, tartaric acid, citric acid, oleic acid, stearic acid, Nolactic acid, and mixtures thereof, or a salt of an acid selected from the group consisting of substituted or unsubstituted, aromatic carboxylic acids such as benzoic acid, salicylic acid, and mixtures thereof, having from 6 to 20 carbons Is preferably used. Suitable substituents include, for example, hydroxy and / or amino groups.

Particularly preferred catalysts of this embodiment are potassium formate, potassium acetate, potassium octoate, ammonium octoate, 2-hydroxy-N, N, N-trimethyl-1-propane ammonium formate, trimethylhydroxy- Mates, and mixtures thereof.

In a further embodiment of the present invention, it is possible to use an amine-containing compound as catalyst, which likewise catalyses the reaction to form the allophanate, the trimerization to form buret or isocyanurate. Preferred amine-containing compounds according to the present invention include, for example, N, N ', N "-tris (dimethylaminopropyl) hexahydrotriazine (CAS 15875-13-5), tris-3-dimethylaminopropylamine , Pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, trimethylaminoethylethanolamine, dimethylaminoethoxyethanol, 2,4,6-tris (dimethylaminoethyl) phenol, and mixtures thereof .

In this embodiment, N, N ', N "-tris (dimethylaminopropyl) hexahydrotriazine is particularly preferred.

The present invention therefore particularly preferably relates to a process for the preparation of a compound of formula I wherein at least one catalyst used as component (E) is selected from the group consisting of potassium formate, potassium acetate, potassium octoate, ammonium octoate, 2-hydroxy- Propane ammonium formate, trimethylhydroxypropylammonium formate, N, N ', N "-tris (dimethylaminopropyl) -hexahydrotriazine, tris-3-dimethylaminopropylamine, pentamethyldiethylenetriamine, The polyurethane foam of the present invention is selected from the group consisting of methyl dipropylenetriamine, trimethylaminoethylethanolamine, dimethylaminoethoxyethanol, 2,4,6-tris (dimethylaminoethyl) phenol, and mixtures thereof. do.

In addition to the above-mentioned catalysts (component (E)), it is also possible in accordance with the invention to use further catalysts which strongly promote the reaction of isocyanate groups with groups reactive with isocyanate groups. Such catalysts include, for example, strong base amines such as tertiary aliphatic amines, imidazoles, amidines, and alkanolamines.

Component (E) is generally present in the polyurethane foam of the invention in each case in an amount of from 0.1 to 5% by weight, preferably from 0.2 to 5% by weight, based on the sum of components (A), (B), (C) To 3% by weight, particularly preferably from 0.3 to 2% by weight. When a mixture of catalysts is used, a specified amount is applied to this mixture.

For the purpose of the present invention, it is important that the polyurethane foam of the present invention is produced in the presence of a specified catalyst. A particularly advantageous combination of low thermal conductivity and good thermal stability is achieved by this method and by the interaction of the specific components (A), (B), (C) and (D) associated with a particular ISO index.

Component (F):

According to the present invention, formic acid which reacts with blowing agents known to those skilled in the art, for example, water and / or carboxylic acids, especially isocyanate groups to remove carbon dioxide, can generally be used as a blowing agent (component (F)). It is also possible to use a physical blowing agent in combination with water or in place of water. This is a compound that is inert to the starting components and is usually liquid at room temperature and evaporates under the conditions of the urethane reaction. The boiling point of this compound is preferably less than 50 占 폚. Physical blowing agents also include compounds which are gaseous at room temperature and which are introduced into the starting component under pressure or dissolved therein, for example carbon dioxide, low boiling alkanes and fluoroalkanes. These compounds typically contain from 1 to 3 carbon atoms in the alkane and / or cycloalkane, dialkyl ether, ester, ketone, acetal, fluoroalkane having 1 to 8 carbon atoms and alkyl chain having 4 or more carbon atoms Lt; RTI ID = 0.0 > tetramethylsilane, < / RTI > Examples which may be mentioned are propane, n-butane, isobutane and cyclobutane, n-pentane, isopentane and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, Fluoroalkanes which can be decomposed in the troposphere and which do not damage the ozone layer, such as trifluoromethane, difluoromethane, 1,1,1,3,3-pentafluorobutane, 1,1,1, 3,3-pentafluoropropane, 1,1,1,2-tetrafluoroethane, difluoroethane and heptafluoropropane. The physical foaming agents mentioned may be used alone or in any combination with one another.

Component (F) is generally present in the polyurethane foam of the invention in each case in an amount of from 2 to 25% by weight, preferably from 10 to 10% by weight, based on the sum of components (A), (B), (C) By weight to 20% by weight.

In addition to the above-mentioned components, the polyurethane foams of the present invention may optionally comprise further additives known per se to the person skilled in the art, for example crosslinking agents. According to the present invention, the crosslinking agent is a compound having a molecular weight of 60 to 400 g / mol and at least three hydrogen atoms reactive with isocyanate. An example of such a compound is glycerol.

The crosslinking agent is generally used in an amount of from 1 to 10% by weight, preferably from 2 to 6% by weight, based on the sum of components (A), (B), (C) and (E). In a further embodiment, the polyurethane foam of the present invention may comprise at least one chain extender. For purposes of the present invention, the chain extender is a compound having a molecular weight of 60 to 400 g / mol and having two hydrogen atoms that are reactive with isocyanate. Examples of such compounds are butanediol, diethylene glycol, dipropylene glycol and ethylene glycol.

The chain extender is generally used in an amount of from 2 to 20% by weight based on the sum of components (A), (B), (C) and (E).

The crosslinking agents and chain extenders may be used individually or in combination.

Additional additives may include, for example, surface active substances, stabilizers such as foam stabilizers, cell conditioners, fillers, dyes, pigments, flame retardants, antistatic agents, hydrolysis inhibitors, fungistatic and bacteriostatic materials And mixtures thereof.

Suitable flame retardants generally include flame retardants known from the prior art, such as brominated ethers (Ixol), brominated alcohols such as dibromoneopentyl alcohol, tribromoneopentyl alcohol and PHT-4-diol and also chlorinated (2-chloroisopropyl) phosphate (TCPP), tris (1,3-dichloroisopropyl) phosphate, tris (2,3-dibromopropyl) phosphate And tetrakis (2-chloroethyl) ethylene diphosphate.

As further liquid halogen-free flame retardants it is possible to use diethyl ethane phosphonate (DEEP), triethyl phosphate (TEP), dimethyl propyl phosphonate (DMPP), diphenyl cresyl phosphate (DPC) .

For the purposes of the present invention, the flame retardant is present in an amount of from 0 to 65% by weight, preferably from 0 to 60% by weight, more preferably from 0 to 60% by weight, based on the sum of components (A), (B), 0 to 50% by weight. When a flame retardant is present according to the present invention, it is present in an amount of from 2 to 65% by weight, preferably from 5 to 60% by weight, more preferably from 5 to 60% by weight, based on the sum of components (A), (B), Is used in an amount of 5 to 50% by weight.

For the purpose of the present invention, the ratio of the OCN group to the OH group known as the ISO index in the reaction mixture for preparing the polyurethane foam of the present invention is from 140 to 180, preferably from 145 to 165, particularly preferably from 150 to 160 It is also important. This particular ISO index, which in combination with other specified features important to the present invention, results in a polyurethane foam having a particularly advantageous combination of low thermal conductivity and thermal stability.

The present invention also provides a process for producing a polyurethane foam according to the invention comprising at least the following steps:

(I) contacting the components (A), (B), (C), (D), (E) and (F)

(II) foaming the reaction product obtained in step (I).

Methods of making polyurethane foams are known per se to those skilled in the art. For example, the polyurethane foam of the present invention can be produced by a prepolymer process or preferably by a one-shot process (steps (I) and (II)) using a known mixing apparatus May be prepared batchwise or continuously.

The process according to any one of the preceding claims, wherein in step (I) a two component process is used and the formative components (A), (B), (C), (E) and (F) It has been found to be particularly advantageous to react this with the polyisocyanate (D) to foam the mixture. An overview of the production of polyurethane foams and their use as a covering layer or preferably a core layer in composite members and their use as insulating layers in cooling or heating technology, , Corresponding chapter (s) of, for example, Kunststoffhandbuch, volume 7 "Polyurethane ", edited by Gueter Oertel, Carl-Hanser-Verlag Munich, 1st edition, 1966, 2nd edition, 1983 and 3rd edition, It is public.

Further, the present invention also includes the use of the polyurethane foam of the present invention for insulation, especially for pipe insulation.

The polyurethane foam of the present invention is preferably used for insulation of pipes, for example, district heating pipes.

In a preferred embodiment, the polyurethane system of the present invention is used for insulation of insulated composite jacketed pipes for district heating networks embedded in accordance with DIN EN 253.

The present invention further provides an insulated pipe comprising a polyurethane foam according to the invention. The insulated pipe of the present invention is made, for example, as follows:

I) pipe for medium,

Ii) a layer of insulating material comprising the polyurethane foam of the present invention, and

Iii) the outer pipe.

The medium pipe (i) is generally a steel pipe having an outer diameter of 1 to 120 cm, preferably 4 to 110 cm, and a length of 1 to 24 meters, preferably 6 to 16 meters.

The layer (ii) of the insulating material comprising the polyurethane foam of the present invention is arranged outside the pipe for the medium. This layer generally has a thickness of 1 to 10 cm, preferably 2 to 5 cm.

In a preferred embodiment, the layer of insulating material has a total bulk density of less than 90 kg / m ³ , preferably 70 to 87 kg / m ³ . For this purpose, the overall bulk density is a bulk density distribution over the pipe section and pipe length.

In a further preferred embodiment, the layer (ii) of the insulating material comprising the polyurethane foam of the invention has a thermal conductivity of less than 27 mW / mK, preferably 22 to 26.9 mW / mK, measured according to EN ISO 8497 I have.

The outer pipe (iii) surrounds the layer of insulating material and generally comprises plastic, for example polyethylene, and typically has a thickness of 1 to 30 mm. The inner diameter of the outer pipe is generally 6 to 140 cm, preferably 10 to 120 cm.

The outer pipe (iii) may comprise a plurality of layers optionally combined in an extrusion operation. An example thereof is the introduction of a multilayer film between a polyurethane foam and a PE sheath, wherein the film comprises at least one metal layer for enhancing barrier action. Suitable outer pipes of this kind are described in EP-A-960 723.

In a particularly preferred embodiment, the insulated pipe is an insulated composite jacketed pipe for buried district heating networks, which meets the requirements of DIN EN 253.

Example

The present invention is illustrated by the following Examples.

Formulation 1-2 is according to the present invention, and 3-5 is a comparative formulation.

Polyether A: Starting with sucrose, pentaerythritol and diethylene glycol, alkoxylated with PO; OH = 403 mg KOH / g, action = 3.9

● polyether B: starting with sorbitol, alkoxylated with PO; OH = 490 mg KOH / g, action = 4.9

Polyether C: Start with TDA, alkoxylated with PO and EO; OH = 390 mg KOH / g, action = 3.8

● polyether D: starting with glycerol, alkoxylated with PO; OH = 805 mg KOH / g, action = 3

Polyester A: esterification product of phthalic anhydride, diethylene glycol and oleic acid, OH = 210 mg KOH / g, functionality = 2

DPG: dipropylene glycol, OH = 840 mg KOH / g; Action = 2

● Silicon-based stabilizer (L 6900 from Momentive)

Catalyst 1: Dimethylcyclohexylamine

Catalyst 2: N, N ', N "-tris (dimethylaminopropyl) hexahydrotriazine

Catalyst 3: Potassium acetate (47% in ethylene glycol)

A mixture of diphenylmethane 1,4'-diisocyanate and high oligomeric oligomers and isomers (Crude MDI), an NCO content of 31.5% by weight, and an average functionality of about 2.7, IsoPMDI 92140 from BASF SE.

The table shows that the use of the rigid PU foam system according to the present invention significantly improves the thermal conductivity at constant thermal stability.

Analysis method:

The measurement of the thermal conductivity of the composite jacketed pipe DN 50 was carried out in accordance with DIN EN 253: 2006-02, Annex G and ISO 8497.

The aluminum flask was manually filled (equivalent to a foam density of 80 kg / m < ³ >) with a foam amount of 210 g. The flask was completely sealed using screw caps. The foamed aluminum flask was stored at 180 DEG C for 30 to 40 days. After opening the aluminum flask with a saw, the change in color and cell structure was visually evaluated.

The glass transition temperature was measured using dynamic mechanical analysis (DMA). The maximum loss factor (tan δ) was chosen according to the glass transition temperature.

Claims (8)

(A) at least one polyether polyol as component (A) based on at least one compound selected from the group consisting of trimethylolpropane, glycerol, pentaerythritol, a sugar compound and a mixture thereof;
(B) at least one polyether polyol based on at least one amine as component (B)
(C) at least one polyester polyol as component (C) and
(D) at least one polyisocyanate as component (D)
In the presence of at least one catalyst selected from the group consisting of salts of carboxylic acids having 1 to 20 carbon atoms as component (E), amine-containing compounds and mixtures thereof, and at least one blowing agent as component (F) , The ratio of OCN group to OH group (ISO index) is 145 to 165. The polyurethane foam according to claim 1, wherein the at least one amine in component (B) is toluene diamine (TDA). The composition of claim 1 or 2, wherein the at least one polyether polyol (a1) based on the polysaccharide sugar, at least one polyether polyol (a2) based on the monosaccharide sugar, and at least one A polyurethane foam in which a mixture comprising polyether polyol (a3) is used as component (A). A process for producing a polyurethane foam according to claims 1 or 2 comprising at least the following steps:
(I) contacting the components (A), (B), (C), (D), (E) and (F)
(II) foaming the reaction product obtained in step (I). Use of the polyurethane foam according to claims 1 or 2 for insulation. 6. The method of claim 5, wherein the insulation is pipe insulation. An insulated pipe comprising the polyurethane foam according to claims 1 or 2. The polyurethane foam according to claim 1, wherein the sugar compound is selected from the group consisting of glucose, sorbitol, mannitol, and sucrose.